Mold and method of making molds



Oct. 28, 1952 A. R. BLACKBURN ETAL 2,615,229

MOLD AND METHOD OF MAKING MoLDs Filed Nov. 12, 1948 v 2 SHEETS-SHEET 1 ATTORNEY;

Oct. 28, 1952 A. R. BLACKBURN ETAL MOLD AND METHOD OF MAKING MOLDS Filed NO V. 12. 1948 ATTOR N Eys Patented ct. 28, 1952 MOLD AND METHOD OF MAKING MOLDS Andrew R. Blackburn and Richard Steele,

Columbus, Ohio, assignors to Ram, Inc., De-

troit, Mich.

Application November 12, 1948, Serial No. 59,492

(Cl. .Z-129) 8 Claims.

The present invention relates to molds and methods 'of forming molds for use in the manufacture of ceramic ware, and has particular reference to improvements in porous molds of the type embodying conduit means embedded in the body of the mold for carrying fluid pressures to the mold face to effect the separation of the molded object from the faces of the molds immediately `upon formation and independently of ware shrinkage. The present invention is an improvement on the mold and method of manufacture disclosed and claimed in application Serial No. 737,544, entitled Mold and Method of Making Same, liled March 27, 1947 by Andrew R. Blackburn and Richard E. Steele relating speciiically to improvements in the uid pressure conduits embedded in the porous mold.

Air release molds of the type disclosed in thev above-identied application for .patent are adapted for continuous use in assembly line ware forming operation. Due to wear on the mold face, it is necessary to reform the mold in order to maintain the quality of the ware. In reformation of the mold, it has been found that the air release tubing embedded in the porous body of the mold may become damaged to an extent preventing reuse of the tubing adding considerably to the cost of each mold unit.

With regard to the completed molds, effective separa-tion of the ware from the mold face is dependent in great degree upon careful control of the fluid pressure impressed on the ware at critical points of separation from the mold.

The invention has for an object the provision of a porous mold structure provided with novel conduit means for distributing fluid pressure over desired portions of the facel of the mold, to separate formed Ware fromthe mold faces.

A further object is to pro-vide a mold for use in high speed production of ceramic ware, the mold being available for reuse immediately subsequent to forming the clay object, markedly reducing the number of molds necessary to operate a ceramic ware production line.

A further object is to provide an inexpensive, replaceable fluid pressure conduit for emplacement within'the porous mold base, capable of providing fluid pressure in desired controlled amount at the faces of the molds to effect release of the ware from the mold face, the conduit being formed with means adjustable to provide varying degrees of fluid pressure flow at desired critical points of 4ware contact on the mold face, thereby effecting separation of the Ware l2 without deformation or Abreakage of the most delicate pieces of ware.

A further object is to provide a novel method of forming a mold body embodying a iiuid pressure conduit embedded in a porous mold base.

A further object is'to provide 'a conduitrmem- `ber for use in forming porous'molds embodying the air release principle, which may be reshaped for reuse in successive mold bodies, and which is provided with means for 'adjusting and controlling the flow of fluid pressure to the face of the mold at any point along the length of the conduit.

Other objects and advantages of the invention will be apparent from the following detailed de-A scription thereof, andv accompanying drawings,

Figure 4 is a perspective view of yet anotherform of conduit;

Figures 5 and 6 are perspective views of further embodiments of conduits which may be employed;

and v n Figure 'l is a plan view, partially broken away,

vof the invention.

In its broadest application, the invention embodies the provision of novel fluid conduit means for inclusion in the body portion of a porous mold to be employed in the manufacture of ceramic.

ware. The uid conduit members normally are positioned in the mold body so as to follow in spaced, parallel relationshipthe contour of the molding surfaceY impressed on the mold face,

whereby 'upon the application of fluidl pressures to the conduit, a blanket of fluid pressure emerges in controlled amount from the mold body adjacent the mold face to separate the formed wareffrom i the mold. Molds formed in accordance With the present invention are constructed toy provide for a more effective and minute degree of control of the amount of fluid pressure yimpressed upon a selected portion of they molded object, whereby cracking or deformation of the molded object during the removal step is avoided. The pressure conduits of the invention are so constructed that they may be modified in cross sectional area by the mold maker during assembly of the mold to provide a desired fluid pressure at a preselected point or points on the body of the ware. Accordingly, it will be seen that the pressure conasias@ 3 duits of the invention may be constructed by the mold maker in accordance with predetermined pressure release requirements for a particular piece of ware, and then reformed and readjusted for use in another mold.

The invention also contemplates the provision of fluid pressureconduits formed of .ineii'pensive materials'which may `be disposed of after use without appreciably affecting the cost per unit of the completed molds.

The term fiuid pressure is used hereinafter in its broad sense, embodying' the use ofV air or hydraulic pressure. For purposesrof description, however, the invention will be described in 'connection with the use of air pressure in effecting the quick release of ware from the mold surfaces.

Referring to the drawings, there is yshown in Figure 1 an exemplary form of mold comprising male and female mold sections indicated generallyas It! and II, each section having a base plate I2 supported by a memberISj such as a hydraulic plunger for effecting relative` movement of the mold sections. The plates, I2 support mold ringsl Ill secured theretoby screws I5 or otherwise. :Each mold section is formed Awith amold body I6 composed of a porous material characterized by extreme hardness such as a high grade plaster of Paris. The mold bodies llII are formed with male and female forming faces I1 and I8 receiving a body of plasticjclay I9 to be shaped as ware. An excess clayv collecting cavity 26 may be provided, the opposedmold rings I4 also being .provided with'lnife edges 2I for cutting .olf excess clay exuding from between the mold faces. and through the cavity 20, whereby clogging of the molds is avoided. If" desired, stop members' 22 maybe provided adjacent the mold rings IL, to prevent the` application o f excesspressures on the opposed "molds in a ware forming operation.l

One or both of the molds mand I, lare provided with fluid pressure means comprising a pressure conduit 23 spaced apart from andv parallel to the plane of the impression 4contour on the faces I'i and I8 of the molds., .Theconduit 23 extends through the mold rring M at 24 for connection with a source of fluid pressure not shown providing a positive pressure` or a vacuum pressure in the conduit 23, as desired.v It will be seen that theconduit A23 is positioned with relation to the face of the porous mold body as to provide a uidV pressure of Y predetermined strength emanating from the entire mold face adjacent the ware formed on the, mold, upon the application of fluid pressure. Theconduit A23 is positioned by the mold makerduring `construction of themoldy whereby .av `desirednuid pressure is provided at points on the mold face and correlatively on the face of thel adjacent clay object, the points being ,selected in accordance with the points `of relative structural strength 'of the clay object,. Y o Y Y* In accordance with the present invention,

vmember 25A preferably is positioned the porous material such as a fabric Yof Vrelativelytigl'it j found that the conduit 23 may advantageously mold body so that the perforations 26 or open seam 21 open towards a desired portion of the ware nearest the tube 25, thereby assisting in the direction of theflow of pressure. As shown best in Figure 1, the uid pressure preferably is directed at the stronger portions of the ware I9 such as the ware base 28, capable of receiving the force of the fluid pressure without fracture, or deformation.

To assist in the release and control of the ow ofthe fluid pressure from the conduit 23 into and through the porous mold bodies to the mold faces, novel means are provided to form a pressure chamber l2,9 of cross sectional area greater than that Vof the conduit 23 in the mold bodies around the conduits 23 and along the length thereof. The chamber forming means preferably may comprise a member expansible and contractible longitudinally'of the conduits 23 whereby the cross sectionalarea of the chamber defined by the member is correspondingly decreased and increased, forming a pressure charnber of desired cross sectional area around the conduit 23 in the mold body. Adjustment of the chamber forming means is accomplished-by the mold maker, during the formation of the mold, as the gypsum or other material employed in forming the mold is being put into themold casing. 'a y l A preferred embodiment of pressurefchamber forming means is shown in Figures 2, 3 and 6 of the drawings, and comprises a tubular sleeve 3i] superimposed over the length of the tube 25 and movable longitudinally of the tube. `The sleeve 30 may be formed of a porous-resilient flexible weave, having sufiicientjbody iii/expanded or contracted position to withstand distortionor compression by the vweight of the plaster forming the moldA body, maintaining the cross sectional area desired. The; tubular sleeve v30 mayr preferably be formed of chemically resistant fibers or threads such as glass or rayon, and'may be of a length equal to'the length of the lt'ube"`25`or consistent with the particular pressure frele'ase requirements Aof, the mold.l The sleeve' 3l] lmay be secured atterminal portions and at points along the length thereof by suitable bindings 3l, which permit of movement of any desired portion lofthe Ysleeverelativev to-the tube 25,2wh`ereby adjustment of the sleeve is accomplished.

'As shown in Figure 2, when it is desiredl that the pressure chamber 29be of yreduced cross section approachingthe cross sectional area' of the tube 25, the sleeve bindings 3l defining the enlarged section of the sleeve are moved away from vproviding a pressure chamber 29 ofnincreased cross sectional area around ahdesired portion of the tube 25. y *o Referring to Figure 6, in cases where the molds have to be reformed frequently, it has been comprise a resilient coil of wire 32Ak which may temporarily be def'rined'-by the moldv maker in accordance with the requirements of' a particun aanmeld refining; prcdure, thewir'e 'een' '32 returning tolnrmal'fs'hape whenthe" mold is broken up. In this case, 'it is pr'eferredfthat the sleeve 3u` einen@ me fun lengte or mee-01132. ggeidispensible ferm@ 6L enduit 2.3 Which may remanufactured inexpehsiviy is shown ni 'F1-gure 5. vThe conduit 23 embodies a rope 33 of loose lfibrous material such as cotton batten, secured b'y'aloosely Woven net 34, the rope 33 preferably being formed around a supporting wirel 3 5 forming a relatively rigid core member,

v`assisting in formation of the conduit 23 into a desired shape. The diameter of the rope may be modified simply by stretching or compactinf,r the member as it is emplaced in the soft plaster body of the mold prior to hardening.

Application of the principles of the invention to a mold section for the formation of an approximately squareclay dish is shown in Figure '7, employing the perforated tube 25 as the fluid pressure conduit. It Will be noted that the sleeveSi! is shown as expanded or bunched at 35 `on desired portions of the tube 25 which may be adjacent the corners or at other selected portions of the dish I9. The enlarged cross sectional areaof ythe uid pressure chamber around the tube 25 invthese expanded sections 36 results in an increased iiuidpressure being impressed on these particular portions of the Ware to effect the separation thereof from the mold face. A minimum of pressure is applied to the relatively Weak portions of the dish more readily deformed or cracked by the pressure, by those sections of the tube 25 Where the sleeve is eX- panded along its length iiush with the tube sur'- face to provide a pressure chamber 29 of minimum cross sectional area. A further type ofsleeve arrangement is shown in Figure 1 of the drawings wherein a minimum of pressure is eX- erted against the bottom center portion of the Wire.

Formation of the molds may be accomplished in accordance With the method disclosed in application Serial No. 737,544.

It will be observed that the present invention permits of use of the pressure, release principle in the manufacture of the most delicately formed piecesof Ware, by providing means for affecting a ne degree of control over the application of fluid pressure to selected portions of the Ware. 1n addition, the pressure conduits of the invention are protected against, the introduction of small pieces of solid matter into the pressure conduits, which might tend to clog the conduits, when a vacuum is applied to the conduits. rI'he invention also provides an inexpensively formed pressure release conduit, which may be used repeatedly in mold forming operations, or which may be discarded without appreciably increasing the cost per mold. It will be apparent that the invention may be practiced in the manufacture of Ware of any shape or size, and in connection with any mold embodying a porous base.

It will be apparent that obvious substitutions of materials may be made without departing from the spirit of the invention, which is to be limited only as defined in the appended claims.

We claim:

1. In a mold for use in the formation of Ware, a porous mold body and means in the mold body for supplying uid pressure at the face of the mold to effect release of the formed ware comprising a flexible, porous conduit embedded in the porous mold body of varying cross-sectional area at selected points along its length to control the amount of fluid pressure delivered through the porous mold body to the mold face at said selected points along the length of the conduit.

2. In a mold for use in the formation of Ware,

a porous mold body and means in the mold body for supplying fluid pressure at the face of the mold to effect release of the formed Ware comprising an expansible and contractible conduit embedded in the porous mold body in spaced relationship with the face of the mold, said conduit having a cross-section area varying at selected points along the length of the conduit to control the amount of fluid pressure delivered through the mold body to points on the porous mold face opposite the said modified sections of the conduit.

3. In a porous mold for use in the formation of ceramic ware, a porous mold body andv means for supplying fluid pressure at the face of the mold comprising an apertured tube in the porous mold body for receiving and dispersing fluid pressure through the mold body to the mold face, and a permeable cover member having a cross-section varying along its length enveloping the tube and forming a fluid pressure chamber between the surface of the tube and the surrounding porous mold body.

4. In a porous mold for use in the formation of a ceramic Ware, a porous mold body and means for supplying fluid pressure `at the face of the mold comprising a tubular conduit in the porous' mold body for receiving and apertured for dispersing uid pressure through the mold body to the mold face, and a Woven fabric sleeve on the conduit, said Woven fabric sleeve having a non-uniform diameter to form a pressure chamber of desired cross sectional area between the surface of the tubular conduit and the porous mold body adjacent the conduit whereby the fluid pressure directed to selected points along the face of the mold is controlled.

5. n a mold for use in the manufacture of ceramic Ware, a porous mold body and a fluid pressure conduit embedded in the mold body for effecting the pressure release of Ware from the mold body comprising a tubular member apertured along its length for the release of uid pressure in the mold body, and a Woven fabric sleeve of non-uniform diameter on the tubular member forming a chamber of non-uniform diameter around the tubular member Within the mold body. f

6. A method of incorporating a fluid pressure conduit in the body of a porous mold of plastic material While in the plastic state comprising shaping the conduit to parallel roughly the surface contours of the object to be molded, modifying the cross sectional area of the shaped conduit at selected points along its length to increase the surface area of the conduit in contact with the porous mold body at spaced points, incorporating the shaped conduit in the plastic mold body, impressing a molding contour on the Surface of the plastic body in spaced relationship with the conduit, and hardening the mold body.

7. A method of forming a uid pressure conduit Within the body of a porous mold for purposes of supplying controlled fluid pressure across the face of the mold to release a piece of formed Ware therefrom, comprising shaping the conduit as a coiled member conforming generally to the surface contours of the object to be molded, enlarging the cross-sectional area of the conduit at selected points along its length wherein it is desired to apply locally an increased fluid pressure to the mold face to assist in ware removal, forming a plastic mix of mold forming material, in-A corporating the preformed fluid pressure conduit 1n the plastic material, impressing a molding contheV plastic Amaterial in tionedxdirectly overxthev portion of thel conduit having-"enlarged cross-sectional areas iwhereby an. `increased .fluid pressure: is. directed A'through the` porouszmoldfbody to' thezsaid localized areas, .and hardening the: mold.

' 8. A: method of forming: a iuid `pressure Yconduit within lthe body .oa porous moldv fori purposes of. supplying'controlled fluid pressure across the face of the mold to releasea piece of. formed f Ware vtherefrom comprisingxshaping. an. apertured v.lc:onduitghaving-v asleeve-of. porous material comipressible..longitudinallyto 'forms a lsleeve of in- -creased"diameter thereon as a coiled `member conformingv generally yto the surface contours `of the objectto be molded,.longitudinally compressing the .sleeve at selected points` along. itszlength wherein itisizdesi-red tozapply locally an increased fluid:pressureitmthef-mold face to assist .in Ware removal, securing thesleevev to ythe conduit at the extremities of .the compressed Yportions vto x l the.` position of the f compressed f portions on the condition, shaping the surface ofthemoldr body in spaced relationshipy .With- .theconduit lWith selected localized` areas ot themolding fcontour being positioned directly over the, longitudinally compressedV portions of the cond-uit-whereby,an increaseduid pressure may-be directed. through the porousmold body to the-said localizedv areas,

and hardening the mold body.

ANDREW R. BLACKBURN. RICHARD E;.STEELE.

REFERENCES CITED The following arieferen'cesare'. ofirecorclinzihe rile' of this patent:

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